A tilt position adjustment mechanism is a mechanism for adjusting an inclination angle of the steering wheel to the best driving position according to the body type or preference of the driver. In adjusting the inclination angle of the steering wheel, after the inclination angle of the steering wheel is adjusted steplessly in a state where a tilt clamp mechanism is unclamped once, the tilt clamp mechanism is again clamped.
In the steering device having the steering position adjustment mechanism of this type, a vehicle body attachment bracket is fixed to a vehicle body, and a fastening rod is allowed to insert into a tilt adjustment slender groove and a column of the vehicle body attachment bracket. During tilt clamping, a stationary cam is pressed in an axial direction by a movable cam that rotates due to the operation of an operating lever to fasten the fastening rod, and the column is pressed toward the vehicle body attachment bracket for clamping. However, when the fastening force of the fastening rod is low, the column is caused to move in a tilt direction during a secondary collision where a driver collides with the steering wheel, resulting in a risk that an air bag disposed in the steering wheel cannot accept an occupant at an effective position.
As a mechanism for blocking the movement of the column during this secondary collision, there is a tilt lock mechanism in which a stationary tilt lock gear is disposed on the vehicle body attachment bracket side, and a movable tilt lock gear the is engaged with the stationary tilt lock gear is inserted into the fastening rod.
With this configuration, during the tilt locking, the fastening rod is fastened to engage the movable tilt lock gear with the stationary tilt lock gear, thereby improving a retention force in the tilt direction, with the result that even if an impact load due to the secondary collision is exerted on the steering wheel, the column is not moved in the tilt direction.
In the above steering device that enables the tilt position to be adjusted steplessly, when the fastening rod is fastened to engage the movable tilt lock gear with the stationary tilt lock gear during tilt locking, there occurs a phenomenon that the respective threads of the movable tilt lock gear and the stationary tilt lock gear may be abutted against each other depending on the tilt position. When the respective threads of the movable tilt lock gear and the stationary tilt lock gear are abutted against each other, the tilt lock becomes insufficient, and when the fastening rod is forcedly fastened, the movable tilt lock gear and the stationary tilt lock gear are strongly rubbed with each other, thereby causing discomfort for the driver.
In a steering device having a tilt clamp mechanism of Patent document 1, the movable tilt lock gear is fitted onto the movable cam with a gap therebetween, an annular elastic member is inserted between the movable cam and the movable tilt lock gear, and a washer made of resin is inserted between the movable tilt lock gear and the operating lever for fastening to the fastening rod. This enables the movement of the movable tilt lock gear to the movable cam in the tilt direction, and provides the degree of freedom of a position at which the movable tilt lock gear and the stationary tilt lock gear are engaged with each other.
However, in the steering device having the tilt clamp mechanism of patent document 1, because the annular elastic member is inserted, there is a risk that the movable tilt lock gear falls with respect to the stationary tilt lock gear, and the engagement of the movable tilt lock gear and the stationary tilt lock gear is defective. Also, because the annular elastic member is compressed during the tilt clamping, it is not easy to select a material having a sufficient durability from elastic materials such as rubber as the material of the annular elastic member.